1. Field of the Invention
The invention relates to a custom fitting assembly for a helmet. The system is particular suited for use with helmet mounted devices which support military air and ground operations.
2. The Prior Art
In general, helmets are designed to meet requirements for comfort, stability, and head impact protection during flight, egress and ejection, and to fit an anthropometric range of heads. With the advent of helmet mounted devices (HMS) an increased demand for optical stability was required to keep the HMD in the operator's field of view. This created various designs of inner liners and improved suspension systems to meet the comfort, stability and weight bearing requirements of the many HMDs.
Improvements in electro-optics technologies promised to transfer aircraft mounted head up displays and HMD imagery to the inner surface of the helmets visor or to other optical display combiner or device. With new Helmet Mounted Display (HMD) technologies comes a new and even tighter requirement for optical stability. Current helmets have been used to launch these new technologies with little success. The weights and center of gravity of new HMD systems displace the helmet out of the "eyebox" thereby negating the HMD's operational effectiveness as well as causing aircrew fatigue, neck strain, and during ejection possible severe injury and death.
An example of a prior art design is described in U.S. Pat. No. 5,584,073. A serious drawback with such platform is that to achieve a high level of stability, the suspension had to be tightened to the point of wearer discomfort. While the suspension system was tight it still swayed under "G" loading with HMD weights. Due to the narrow headband, the load bearing areas around the head created numerous areas of discomfort, known as "hot spots". Additionally, each HMD system requires exact and repeatable placement of the image in front of the wearer's eyes, which must be maintained during the entire mission and over many missions. Designers concluded that meeting such criteria with existing systems could not be practically achieved and would require an impractical number of helmet sizes to properly fit a large anthropometric head population.
Accordingly, it would be desirable to provide an inner helmet assembly in just a few sizes which could be easily custom-fitted to military personnel for use with various outer helmet systems for a variety of modern combat applications. Such an inner helmet would figuratively lock onto the wearer's head thereby insuring reproducible alignment of the "eyebox" to the eventual HMD.